Method of forming a waveguide in diamond

ABSTRACT

N-V centers in diamond are created in a controlled manner. In one embodiment, a single crystal diamond is formed using a CVD process, and then annealed to remove N-V centers. A thin layer of single crystal diamond is then formed with a controlled number of N-V centers. The N-V centers form Qubits for use in electronic circuits. Masked and controlled ion implants, coupled with annealing are used in CVD formed diamond to create structures for both optical applications and nanoelectromechanical device formation. Waveguides may be formed optically coupled to the N-V centers and further coupled to sources and detectors of light to interact with the N-V centers.

CLAIM OF PRIORITY

This application is a continuation of U.S. application Ser. No.11/996,482, filed Nov. 19, 2008 (issued as U.S. Pat. No. 8,058,085)which is a U.S. National Stage under 35 U.S.C. 371 of InternationalApplication No. PCT/US2006/027196, filed Jul. 11, 2006, which claims thebenefit of priority under 35 U.S.C. 120 to U.S. application Ser. No.11/178,623, filed Jul. 11, 2005 (issued as U.S. Pat. No. 7,122,837), allof which are incorporated herein by reference in their entirety.

BACKGROUND

Common computers provide digital processing in which data are held inpositive or negative states (or off and on states) of a device. Digitaldevices can be semiconducting, magnetic, optical, piezoelectric or otherdevices. This is referred to as digital computing and it is the economicand technical heart of all current computers, semiconducting devices forcomputers and computer software. The act of using a digital technologyrequires that all data must be identified as powers of “2”, this in turnrequires that data manipulation, speed, storage, etc that expand at thisenormous rate.

This digital route requires significant increases in semiconductor chipsize, speed and complexity to accommodate even modest improvements inperformance. Semiconductor engineers have responded by making devicessmaller and with smaller spacing with larger numbers of devices and everincreasing complexity. The requirements for smaller spacing have pushedthe limits of material and photolithography capability and it isestimated that we are reaching the limits of Moores Law (which statesthat devices will continue to decrease in size and double in capacityevery 18 months); in addition, the amount of heat produced by decreasingdevice spacing is imperiling device performance. The digital computer israpidly becoming too large and too complex for large numbermanipulations such as weather analysis, high level encryption, drugdiscovery, genetic manipulation and many other applications as yetundiscovered because of the limitations on digital computers.

An entirely new type of computer has been proposed which is based onquantum behavior. The spin state of an atom or group of atoms can bemanipulated using a number of methods and the spin state can bedetected, and/or controllably altered, using an energy source ordetector such as an optical source or detector. An atom or atoms withdiscrete spin states are analogous to a bit in a traditional computer.However, due to the quantum nature of the spin states, a quantum bit (orqubit) can exist in not just one of two states, but also in asuperposition of these states. It is this superposition of states whichmakes it possible for qubit based computers to analyze information at amuch greater speed than is possible for traditional computers.

The name Qubit is quite generic in that devices can be made which use(and need to use) only one Qubit whereas others may use many Qubit s.Devices which have been proposed include single Qubit optical amplifiersfor encrypted and very high speed messages, multiple Qubit devices forinformation storage, and multiple Qubit devices for high speed and highdensity computing. Because the atom can exist in a large number of spinstates simultaneously, the interaction of spin states enables a highnumber of computations with only a small number of atoms. The entireQubit chip of a supercomputer might well be smaller than a fingernail.In addition, Qubit technology holds promise for combining with opticalwaveguide technology building high speed optical busses for conventionalcomputers while in creasing encryption capabilities.

Magnetic spin states can be generated in a large number of materialsincluding liquids and solids. However to be useful for a quantumcomputer, several conditions must be met; 1. The spin state must becapable of being excited; 2. The spin state must be detectible; 3. Thespin state must have a lifetime which is long enough to permit theintended calculation to be done and the result to be detected; 4. Thedevice must operate at a practical temperature.

A large number of materials have been proposed for use as Qubit hostsincluding semiconductors (including quantum dot semiconductors) andsuperconductors. All of these materials to date have the disadvantage ofoperation at cryogenic temperatures and or having short spin lifetimes.It has been discovered that the N-V center in diamond had not only thelongest spin lifetime of any material but it had this property at roomtemperature. An N-V center is nitrogen in a substitutional site indiamond which is adjacent to a carbon vacancy. There is an N-V⁻ centerwith a negative charge, an N-V⁰ center which is similar but has nocharge and a Ns center which is nitrogen substituted for carbon with noadjacent vacancy. The N-V center typically is in one of two chargestates, negatively charged N-V⁻ and neutral N-V⁰.

The N-V center in diamond has several attributes which make it desirablefor Qubit based devices. It is easily pumped using low power microwaves.It is also easily detected (emission at 675 nanometers wavelength). SuchN-V centers in diamond may have long lifetimes (60 to 500 microseconds)and room temperature operation. Diamond also has a high degree ofoptical transparency and a high optical index of refraction, enablingconstruction of optical waveguides and other optical structures.

SUMMARY

N-V centers in diamond can be created in a controlled manner. In oneembodiment, a single crystal diamond is formed using a CVD process, andthen annealed to remove N-V centers. A thin layer of single crystaldiamond is then formed with a controlled number of N-V centers. The N-Vcenters form Qubits for use in electronic circuits.

Masked and controlled ion implants, coupled with annealing are used inCVD formed single crystal diamond to create structures for both opticalapplications and nanoelectromechanical device formation. Ionimplantation is employed to deliver one or more atomic species into andbeneath the diamond growth surface in order to form an implanted layerwith a peak concentration of atoms at a predetermined depth beneath thediamond growth surface. The composition is heated in a non-oxidizingenvironment under suitable conditions to cause separation of the diamondproximate the implanted layer. Further ion implants may be used inreleased structures to straighten or curve them as desired. Boron dopingmay also be utilized to create conductive diamond structures.

In one embodiment, a nanochannel is formed by implanting ions in adiamond at a point where the nanochannel is desired. Masks may be usedto control a width and length of the implant, and selected implant powerlevels can be utilized to control the depth of the implant. Heating thediamond causes a separation to occur at or about the implant. Suchseparation may be used as a nanochannel for conveying fluids, or as alow refractive index portion of a waveguide.

Further implants may be sized and shaped to form an etalon, opticalfilter, or optical deflector. An approximately 500 nm circular shape isused in one embodiment. Using a progression of masks and implant depthscan provide for formation of many different mechanical structures, suchas those that may be formed in silicon. Further layers of syntheticdiamond of one or more diamond layers may be grown following theimplants.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block representation of a diamond having an N-V centeraccording to an example embodiment.

FIG. 2 is a side view cross sectional representation of a diamondillustrating a masked ion implant process according to an exampleembodiment.

FIG. 3 is a top view of the diamond of FIG. 2, illustrating the mask forion implantation according to an example embodiment.

FIG. 4 is a side view cross sectional representation of the diamond ofFIG. 2 following the ion implant and heating according to an exampleembodiment.

FIG. 5 is a side view cross sectional representation of a diamondillustrating a masked ion implant process for forming a cantileveraccording to an example embodiment.

FIG. 6 is a top view representation of an ion implantation mask used toform a cantilever according to an example embodiment.

FIG. 7 is a side view cross sectional representation of a releasedcantilever according to an example embodiment.

FIG. 8 is a side view cross sectional representation of a masked diamondfor forming optical structures according to an example embodiment.

FIG. 9 is a top cross sectional view of the diamond of FIG. 8illustrating optical structures formed according to an exampleembodiment.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration specific embodiments which may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized and that structural, logical andelectrical changes may be made without departing from the scope of thepresent invention. The following description is, therefore, not to betaken in a limited sense, and the scope of the present invention isdefined by the appended claims.

N-V centers in diamond can be created in a controlled manner. In oneembodiment, a single crystal diamond is formed using a CVD process withnitrogen included in the growth process, and then annealed to remove N-Vcenters. A thin layer of single crystal diamond is then formed with acontrolled number of N-V centers. The N-V centers form Qubits for use inelectronic circuits.

Qubit devices are formed in diamond having highly controlled purity. Ahighly controlled number of N-V centers can be produced, and the N-Vcenters are isolated from each other and from other elements having amagnetic spin such as N-V0, Ns and 13C (carbon 13). In one embodiment,single, isolated N-V centers are used to obtain information fromindividual atoms rather than from clusters. In further embodiments, itmay be desirable to have N-V adjacent to 13C. In still furtherembodiments, the diamond has high crystal perfection since imperfectionslead to shorter spin lifetimes and nitrogen tends to segregate atimperfections such as dislocations giving the effect of a higherconcentration and the attendant interaction between adjacent spins andreduction of lifetime.

In one embodiment, light is able to enter and leave the diamond hostmaterial in a controlled manner. When a Qubit emits light, the lightwill be emitted over a spherical surface and the light intensity at anypoint will be very low and difficult to detect. The Qubit is containedwithin an optical waveguide which traps and directs the light in aminimum number of directions. Diamond is ideal for such a waveguidesince it has a very high index of refraction (2.4 in the visible range).A thin layer of diamond in contact with air or vacuum on both sidesprovides such a waveguide. Diamond has a significantly higher index ofrefraction than air, such that a light beam propagating down thewaveguide is internally reflected by the walls of the diamond waveguideand be confined to the diamond waveguide. With the Qubit within thediamond waveguide, most of the light emitted by the Qubit will betransmitted down the waveguide and be readily collected and detected.Other forms of transmission may also be utilized, such as by means of aplasma waveguide or slot waveguide. In still further embodiments, smallmetal wires are utilized to draw light from a Qubit. The lightpropagates on the outside of the wire within a diamond cladding.

One method for building a Qubit device involves growing single crystalsby the HPHT method, incorporating a desired amount of nitrogen atomswhich will all be Ns, irradiating the diamond to generate carbonvacancies and annealing to diffuse the carbon vacancies to the nitrogenatoms thereby causing N-V centers. This method may result in irradiationcausing a significant level of crystal damage which decreases Qubitlifetime.

Another method of producing N-V centers in HPHT diamond involves growingthe diamond with a titanium or aluminum getter to remove all of thenitrogen from the diamond and put nitrogen into the diamond later by ionimplantation into selected spots. This method may not lend itself wellto production of large size diamond wafers which would be suitable fordevice production.

FIG. 1 is a block representation of a diamond crystal lattice 100 havingan N-V⁻ center 110 according to an example embodiment. Center 110 isalso representative of N-V centers with different charge states. Asdescribed above, an N-V⁻ center 110 is nitrogen 115 in a substitutionalsite in diamond which is adjacent to a carbon vacancy 120. In FIG. 1,the N-V⁻ center 110 is isolated from other N-V centers such that spinsof other centers and other structures do not interfere with the isolatedN-V⁻ center, thus forming a Qubit.

The N-V⁻ center 110 in diamond has several attributes which make itdesirable for Qubit based devices. It is easily pumped using low powermicrowaves. It is also easily detected (emission at 675 nanometerswavelength). Such N-V⁻ centers in diamond have long lifetimes (60 to 500microseconds) and room temperature operation. Diamond also has a highdegree of optical transparency and a high optical index of refraction,enabling construction of optical waveguides and other opticalstructures.

One method of producting N-V centers involves the use of CVD growndiamond. CVD diamond can be grown in large sizes with highly controlledpurity as seen in (see U.S. Pat. No. 6,582,513) and with layers ofcontrolled purity, thickness and properties. CVD diamond may be grownwith high or low nitrogen concentrations, thin layers with or without13C. N-V center formation may be controlled by several means.

CVD diamond grows under conditions where N-V⁻, N-V⁰ and Ns are allstable. Furthermore the ratios of these states can be varied by thegrowth conditions, the concentration and by heat treatment after growth.Moreover, it is possible to grow a substrate which is essentially freeof all states of nitrogen and then grow a film of diamond which has onlythe desired level of nitrogen. Since the number of atoms of nitrogen inthe film will be a function of concentration and thickness, N-V⁻ centersmay be isolated from all other centers. In other words, given a knownconcentration of N-V centers that will be formed in a given volume ofCVD grown diamond, making the diamond layer very thin assures that veryfew N-V centers are formed, and are thus isolated from each other.

In further embodiments, a carbon source for the CVD growth of the filmhas a desired level of 13C carbon by either depleting the 13C in thesource gas or by enriching the 13C level. In one embodiment, aseparation of about 2 microns is desired for non interaction between aN-V⁻ and other N centers. This is estimated at about 10 ppb which hasalready been demonstrated. Additionally, a diamond layer of only nominalpurity may be grown and then annealed at high temperature to convert allN-V centers to Ns. This removes any extraneous signal from stray N-Vatoms since Ns does not have an optical signal at the N-V⁻ wavelength.It can also be appreciated that a number of layers can be grown whichare alternating between high purity and specific numbers of N-V centersto obtain a three dimensional structure having isolated N-V in adjacentlayers. Each layer may be designed as a waveguide as described below,and have multiple and separated functions.

In each of the above embodiments, N-V centers may be randomly placed inthe volume of the crystal, but can be readily found and marked fordetection during the operation of the device.

In further embodiments, different types of diamond may be used, such asnatural, mined diamonds, high pressure, high temperature manufactureddiamonds, CVD formed diamonds or others. Such diamond may then beannealed to destroy N-V centers, followed by implantation to createdesired densities of N-V centers, and further implantation to formwaveguides.

An alternate method utilizes very pure bulk crystal with or without thefilm of desired isotopic purity, heat treat to destroy all residual N-Vcenters and then implant single, isolated, N-V centers at desiredlocations. A capping layer of highly pure diamond may then be grown onthe layer.

Waveguides may be formed proximate the N-V centers and optically coupledto them. In one embodiment, Hydrogen is implanted in the diamond instripes, followed by heat treating the structure to create a cavitywhich separates the strip of diamond from the underlying diamond. Thestrip of diamond is essentially surrounded by air and is used as anoptical waveguide for bringing signals into and out of the diamondstructure. It provides a highly isolated optical signal in and out andallows for multiple channels for optical in and out on a single diamondchip. Furthermore multiple functions may be provided, such asamplifiers, storage and computing all on one optical chip. Implant ofmultiple energies may provide multiple strips with separation layersfrom each other, in depth, allowing production of three dimensional,optically isolated Qubit structures. Such structures may significantlydecrease the size of such devices since much of the volume could beutilized. Slot waveguides may also be formed.

It should also be noted that in the case of separated channelwaveguides, that the waveguide can be altered in its properties bycausing the waveguide to rise or fall in spots or along its length byapplication of heat or voltage cycling. This is in essence a fullyattached device. This can be used as a switch to turn off or on thelight or as a switch to move the light to another channel. In oneembodiment, Qubits, optical switching and MEMS technology are combinedinto the same chip with its attendant applications. The use of masked orotherwise patterned implantation and lift-off technology permits thebuilding of a range of waveguide structures such as sheets, plates,wires, disks and multiples of these shapes all with the possibility ofmodulation and switching as in optoelectronic and MEMS devices. It isalso possible to build either normally open or normally closed switchesand mixers by design of the proximity and shape of such waveguides.

Diamond Qubits may also be formed in conjunction with othersemiconductors. Diamond may be bonded to other semiconductors such assilicon, gallium arsenide, gallium nitride, silicon carbide or III-IValloys. The semiconductors can also be grown onto the diamond substrate.The attachment of diamond to other semiconductors will permitoptoelectronic devices such as lasers, detectors and associatedcircuitry to be directly integrated with the diamond QBIT to provideinput and output to and from conventional sources, devices and systems.This will provide the basis for optical busses for higher speedinterconnects in conventional computers and future QBIT based computers.In fact a whole new family of integrated Qubit-Semiconductor devices(QSD) will be possible by combining the technologies and methodsdiscussed.

FIG. 2 is a side view cross sectional representation of a diamondillustrating a masked ion implant process according to an exampleembodiment in order to form a waveguide in proximity to a Qubit formedas above. In one embodiment, the Qubit is an isolated Qubit, and thelocation of the Qubit is used as a guide for forming the waveguide, suchthat the Qubit is located within the waveguide. In further embodiments,the Qubit is formed in an already formed waveguide.

A diamond substrate 210 is covered with a mask 215 in one embodiment.The mask 215 is formed of a material sufficient to screen out ions 220being implanted at desired energy levels. The mask may take manydifferent shapes, but one such shape is shown in top view FIG. 3 at 310.In this embodiment, the mask is in the shape of a long, thin rectangle,resulting in a long thin implant 225 at a desired depth.

FIG. 4 is a side view cross sectional representation of the diamond 210of FIG. 2 following the ion implant and heating to form an open space410 within the diamond 210. Open space 410 provides a low refractiveindex region on one side of a strip of diamond indicated at 420. Theother side of the strip 420 is essentially the top of the diamond 210,which may be exposed to air, also having a low refractive index comparedto the index of refraction of the diamond strip 420. Thus, the diamondstrip 420 forms a waveguide. A Qubit 430 is formed within the strip 420,and the strip provides a mechanism to capture and provide light to theQubit to both detect and effect changes in the Qubit. It is evident thatthe strip 420 may be formed in different shapes, in order to conduct thelight to a desired light source 440 and a light detector 450 which mayeach be further connected to processing circuitry, formed either,within, on, or off of the diamond substrate. The source 440 and lightdetector 450 may also be within, on, or off the diamond substrate invarious embodiments. Optical fiber connections or optical couplers maybe formed to conduct light to an from the waveguide strip 420.

In one embodiment, patterned ion implantation is employed to deliver oneor more atomic species into and beneath the diamond growth surface inorder to form an implanted layer with a peak concentration of atoms at apredetermined depth beneath the diamond growth surface. The compositionis heated in a non-oxidizing environment under suitable conditions tocause separation of the synthetic diamond structure.

Such a non-oxidizing atmosphere generally includes any atmosphere notcontaining a sufficient concentration of oxygen so as to be reactivethrough oxidation. Examples of such atmospheres include inert (e.g.,helium, neon, argon, etc.) and other non-oxygen containing gases (e.g.,hydrogen, nitrogen, etc.). Environments used to provide such atmospherescan include plasmas, vacuums, and the like.

In certain embodiments of the invention, various initial steps can beperformed prior to or concurrent with the ion implantation stage. Onesuch step involves choosing a substrate. When growing single crystallineCVD diamond, for instance, such substrate may be a single crystallinediamond.

Upon selection of the substrate, at least one major surface of thesubstrate can be identified, and optionally prepared, for ionimplantation. Preparation of the diamond surface can include anysuitable means for affecting the chemical and/or physical make-up of thesurface, for instance, by polishing using conventional polishingmethods. Preparation of this sort can be accomplished in advance of theion implantation. Typically, ions are implanted in a manner at a setdistance and even flux across the diamond growth surface, such that theconfiguration of the implanted species layer will itself replicate thesurface profile of the substrate. In turn, any defects on an implantedsurface of the substrate will typically have a corresponding influenceon the implant profile, including on the configuration of thepredetermined peak atomic layer. Thus, such structures may actually besubstantially polished if the surface of the diamond is polished.Preparation of the substrate can be important to initially remove suchdefects. In addition, in certain embodiments, surfaces are thoroughlycleaned for ion implanting, for instance, using solvents or othersuitable methods known in the art, including plasma etching, gas phaseetching and the like. Polishing damage may result in creation ofundesired N-V centers. The surface of the polished diamond may befurther etched to remove such damage and N-V centers.

Ion implantation is generally conducted under conditions of high vacuum,high voltage, and relatively low beam currents. As is known in the art,ion implantation typically involves the process of ionizing a species ofatoms, subsequently accelerating the species in an electric field, anddirecting the accelerated, ionized species toward a substrate. With itsrate of motion being accelerated, the species generally penetrates anouter surface of the substrate and come to rest within a zone in thesubstrate as indicated at 225 in FIG. 2.

The zone is within an implanted layer of the substrate. In oneembodiment, the species is accelerated toward the substrate at an anglegenerally normal or vertical to the surface. However, the species canalso be accelerated toward the substrate at a wide variety of angles aswell. For a given species, the depth of implantation is generallyaccomplished with adjustments made to the electric field. Typically, asone increases the voltage of the electric field, the energy of thespecies is increased, which ultimately results in a deeper implantationby the species into the substrate. It is fully contemplated that thesubstrate may be any of a variety of crystalline shapes. For example,the substrate may be of any predetermined geometry including a cube,cone, prism, pyramid, wedge, or other geometries, as well as frustums ofeach.

The species generally penetrates the upper surface of the substrateuntil reaching a zone, such as zone 225 within the substrate. A peakconcentration of the species is at a certain depth generally known asthe end of range depth. While the species is only shown at the one depth(the end of range depth), it should be appreciated that this is done forsimplicity. Following ion implantation, the species is generallydistributed throughout the zone at and proximate to the end of rangedepth.

Before ion implantation is started, the species to be implanted must beselected. Many variables are considered in selecting a species, such ascost and availability, as well as concern for how much damage thespecies is expected to cause to the substrate lattice, as describedbelow.

During ion implantation, by directing the species (of ionized atoms)into the crystal lattice of the substrate, the implanted portion of thelattice generally dilates or expands. Excessive dilation of the latticein this manner generally leads to strain within the implanted layer.Consequently, excessive strain can cause damage to the implanted layer.This damage is generally represented by dislocations, or cracking,within the implanted layer. These dislocations can generally create anunfavorable outer substrate surface for growing quality syntheticdiamond (e.g., producing diamond via CVD having no defects ordislocations, or insignificant amounts thereof). However, the manner inwhich lattice dilation can be controlled in a number of ways, and infact, relied upon.

One way involves selecting an appropriate species for implanting. Incertain embodiments of the invention, hydrogen ions are implanted withina diamond substrate using the conventional techniques of ionimplantation. Since the covalent radius of hydrogen is small, only asmall amount of lattice dilation occurs within the implanted layer.Consequently, there is little strain (and little damage) within theimplanted layer. Generally, as the covalent radius of the implantedspecies increases, the potential for creating such a favorable surface(e.g., having limited defects or dislocations) decreases.

Generally, any species can be used for ion implanting in the inventiveprocess so long as the species is suitable for subsequently enablingseparation of a portion of the implanted layer from the substrate. Assuch, the species is selected so as to allow for suitable implantationwithin the substrate. Examples of such species include most, if not all,atomic elements. In certain embodiments of the invention, the substrateis also used for growing a synthetic diamond thereon. As such, thespecies preferably allows for suitable implantation within the substrateto enable separation, and allows for suitable formation of a favorablegrowth surface on the substrate from which a quality synthetic diamondcan be grown. Therefore, the species is selected so as to allow forsuitable implantation within the substrate without undesirably damagingthe substrate. Small- to medium-sized species (having small- tomedium-sized covalent radiuses) are generally preferred. Examplesinclude atomic species such as helium, lithium, boron, carbon, oxygen,phosphorous, and sulfur. However, embodiments of the process can alsoinvolve large-sized species (having large-sized covalent radiuses). Insuch embodiments, other parameters affecting the implant of the species,such as species dose quantity and species energy level, are consideredso as to limit the amount of damage to the substrate lattice uponimplantation of the larger-sized species.

The extent of lattice damage to the implanted portion can be limited bythe dose quantity of the species implanted, with the dose being definedas the area density of atoms (atoms/cm²) which are implanted into thesubstrate. For example, if the species is implanted using a high dose,the species will generally cause more damage to the substrate uponimplantation than if a species were implanted using a lower dose. As thespecies (of ionized atoms) travels through the substrate, the damage tothe substrate lattice is generally maximized near the end of the speciesrange into the substrate (generally referred to as “end of rangedamage”).

In turn, the degree of damage at the end of range is a function of thetotal dose at that level. However, the ability to cause separationwithin the diamond crystal is also a function of the total dose. At doselevels that are too low, there will be no separation, while at levelsthat are too high for a particular embodiment, there can be excessivedamage and poor diamond growth. In some embodiments, the dose quantityis set in the range from about 1×10e¹⁴ atoms/cm²to about 1×10e²⁰atoms/cm², and even more preferably, is set in the range from about1×10e¹⁵ atoms/cm²to about 1×10e¹⁸ atoms/cm². When implanting species oflarge sizes, in order to limit lattice damage, it is generallypreferable to choose a dose quantity on the lower end of the range.Conversely, when implanting species of small to medium sizes, any dosequantity within the range is generally suitable.

In addition, the extent of lattice damage to the diamond growth surfacecan be controlled by modifying the voltage of the electric field used inion implantation. As one increases the voltage of the electric field,the energy of the species increases as well, ultimately resulting in adeeper implantation by the species into the substrate. In turn, theenergy level can be selected for a specific species so as to implant apeak concentration of the species at about a certain implantation depthwithin the substrate (the end of range depth). This depth may rangeanywhere from about 500 angstroms to about 20,000 angstroms. While theend of range depth for the species can be limited by decreasing thespecies energy, one ought not limit the energy too severely.

In some embodiments of the invention, the energy level is set in therange from about 10 KeV to about 10,000 KeV, and in another embodiment,is set in the range from about 50 KeV to about 500 KeV. When implantingspecies of large sizes, in order to limit lattice damage of thesubstrate, it may be desired to select the species energy on the higherend of this range. As such, the large size species are implanted furtherfrom the diamond growth surface, thereby attempting to isolate anylattice damage from the diamond growth surface. Conversely, whenimplanting species of small to medium sizes, the method provides morefreedom in selecting the species energy.

The species dose rate may affect the temperature of the substrate duringthe implant. If the dose rate is too high, unwanted graphitization ofthe zone of the implanted layer may occur. In some embodiments of thisinvention, the dose rate is set in the range from about 0.05microamps/cm² to about 100 milliamps/cm², and in others, is set in therange from about 0.1 microamps/cm² to about 500 microamps/cm².

In one embodiment, implants at multiple levels, followed by heating areperformed to create gaps at different levels of the substrate. Oneexample provides three such gaps by implanting H₂ at energy levels of150, 155 and 160 KeV. This can provide three levels of structures, suchas waveguides, with potential corresponding isolated N-V centers.

Given the present description, those skilled in the art will appreciatethe manner in which the end of range depth of the species can bedetermined, given specifics regarding the species implanted and theenergy used. Such calculations are generally known as TRIM (Transport ofIons in Matter) calculations. See J. P. Biersack et al., A Monte CarloComputer Program for the Transport of Energetic Ions in AmorphousTargets, Nucl. Instr. Meth., pp. 174:257 (1980), the teachings of whichare incorporated herein by reference. See also generally J. F. Ziegleret al., In the Stopping and Range of Ions in Matter, Pergamon Press, N.Y., vol. 1 (1985)., the teachings of which are incorporated herein byreference. Table 1 lists the approximate end of range depths for variousspecies at various energy levels, given a diamond seed being used as thesubstrate. Regardless of whether the diamond seed is HPHT, CVD, ornatural diamond, the end of range depths for the species generallyremain the same. As illustrated, as the energy level is increased for aspecies such as hydrogen, its end of range depth is also increased.Calculations were run at an energy level of about 200 keV for speciesincluding boron and carbon to demonstrate that as the atom diameter ofthe species increased, the corresponding end of range depth decreased.In addition, it should be noted that in order to achieve similar end ofrange depths (e.g., 1900 angstroms to 2000 angstroms), energy levelswould have to be increased by a factor of four when using carbon as theimplant species as opposed to hydrogen.

TABLE 1 Implant Depths as a Function of Atom Implanted and ImplantEnergy Implanted Implant Energy Ion/atom 50 keV 100 keV 200 keV 1,000keV Hydrogen 1900 Å 3700 Å 7200 Å 63500 Å Boron 2800 Å Carbon 2000 Å

Heat treatments are provided on the diamond composition in thenon-oxidizing atmospheres. Such treatments can be provided by anysuitable method, including radiation, conduction, or convection sources,all generally known in the art. Generally, the temperature range of theheat treatments is preferably set in the range from about 1100° C. toabout 1800° C. and, more preferably, about 1100° C. to about 1500° C.The combination of the appropriate atmosphere and the temperature levelsprovides an ideal environment to cause spontaneous separation of thesynthetic diamond and the implanted layer portion.

FIG. 5 is a side view cross sectional representation of a diamondillustrating a masked ion implant process for forming a cantileveraccording to an example embodiment. In this embodiment, a first mask isused to form a generally rectangular area which will end up defining thesize of a cavity in which the cantilever will be released to be free tomove. As can be seen, shapes other than rectangular may be used.Depending on the size of elements desired, the implantation depth may bevaried, such that a sufficient density of ions are implanted in theentire area beneath the cantilever and to the sides of the cantilever toallow sufficient motion once the cantilever is released to move. Thus,the mask extends at least slightly beyond the edges and released end ofthe cantilever.

Following ion implantation to form the base of the cavity, a new mask isused as shown in FIG. 6, which is a top view representation of an ionimplantation mask 600 used to form a cantilever according to an exampleembodiment. This mask allows implantation to the sides and past thereleased end of the cantilever, while defining the shape of thecantilever itself with projection 610. The energy levels of implantationused with this mask are designed to implant a sufficient density of ionsto the sides and released end of the cantilever. This implant may varythe depth of implant from the surface of the diamond substrate to thecavity defined below the cantilever. Thus, heating in a non-oxidizingenvironment released the cantilever as shown in FIG. 7, which is a sideview cross sectional representation of a released cantilever beam 710according to an example embodiment. Alternatively, releasing may beperformed using a carbon implant at the edges and etching by oxidationvia heat, electrolysis or oxidizing acid.

In one embodiment, cantilever beam 710 tends to curve upward whenreleased. Further implants in the upper levels may be provided eitherprior to or after release of the cantilever beam. Such implants,depending on depth and density, will begin to straighten the cantileverby putting the surface in compression, and if continued, may actuallycause the cantilever beam to curve downward.

As can be seen from the formation of the cantilever beam 710, many otherthree dimensional structures may be created with the use of one or moremasks, and varying the depths of multiple implants to remove desiredmaterials. Such structures may also be further cleaned in acid solutionsto remove undesired residual implanted diamond material. The structuresmay be used for many different applications, including NEMs and MEMsdevices have general applications. Such devices may be useful as sensorsand other mechanical devices having a wide variety of applicationsbeyond Qubit devices, such as medical devices.

FIG. 8 is a side view cross sectional representation of a masked diamondfor forming optical structures according to an example embodiment. Inone embodiment, the mask 800 comprises an array of one or more multipleround openings 810. The resulting implants at a desired depth followedby heating, forms an array of disk like voids 910, as shown in FIG. 9,which is a top cross sectional view of the diamond of FIG. 8. The disklike voids 910 may behave as a pump, or optical deflector in oneembodiment. When formed near the surface of the diamond, the surface ofthe diamond bubbles up slightly. These bubbles can result in opticalfringe effects, including color changes. In one embodiment, the disksare approximately 500 nm in diameter. Other shapes and sizes may easilybe formed.

In one embodiment, further masks and implants may be used to fullyrelease the diamond above each of the disk like voids, to create smalllens like structures. Such structures may be of desired thicknesses tiedto the implant levels. In one embodiment, the lenses are approximately50 um thick, forming an etalon or optical filter. It should be notedthat lasers and other method of releasing the lenses may be utilized inaddition to varying depth implants and heat to release the lenses. Insome embodiments, thicknesses of less than 1 um are utilized. Thethickness may also be a function of the desired wavelength of operationof the optical device including such structures.

The Abstract is provided to comply with 37 C.F.R. §1.72(b) to allow thereader to quickly ascertain the nature and gist of the technicaldisclosure. The Abstract is submitted with the understanding that itwill not be used to interpret or limit the scope or meaning of theclaims.

What is claimed is:
 1. A method of forming structures in diamond, themethod comprising: forming a first mask on a diamond comprising a maskedportion and an unmasked portion; implanting ions through the firstmask's unmasked portion; forming a second mask on the diamond comprisinga masked portion and an unmasked portion; implanting ions through thesecond mask's unmasked portion; and releasing at least a portion of thestructure formed by the ion implantations.
 2. The method of claim 1wherein the diamond is a single crystal chemical vapor deposition formeddiamond.
 3. The method of claim 1 wherein ions implanted through thefirst mask's unmasked portion define an area beneath the structure. 4.The method of claim 3 wherein ions implanted through the second mask'sunmasked portion define areas lateral to the structure.
 5. The method ofclaim 4 wherein releasing the structure comprises removing the implantedareas beneath and lateral to the structure.
 6. The method of claim 1wherein the structure comprises a cantilever that is free to move. 7.The method of claim 1 wherein the ions comprise hydrogen ions.
 8. Themethod of claim 1 wherein releasing the structure comprises heating thediamond in a non-oxidizing environment.
 9. The method of claim 1 whereinthe ions comprise carbon ions.
 10. The method of claim 1 whereinreleasing the structure comprises etching by oxidation.
 11. The methodof claim 10 wherein the oxidation is performed with heat, electrolysisor oxidizing acid, or a combination thereof.
 12. A method of forming amoveable device in diamond, the method comprising: implanting ions inthe diamond at a desired depth; and heating the diamond to form a voidsuch that diamond remaining above the void is capable of movementrelative to the rest of the diamond.
 13. A method of forming a device indiamond, the method comprising: implanting ions in the diamond at adesired implant depth such that there is diamond above the implantdepth; and heating the diamond in a non-oxidizing environment to form avoid about the implant depth, wherein the diamond layer above the formedvoid bubbles up, forming a convex structure curving away from the formedvoid.
 14. The method of claim 13 wherein the ions are implanted to forma disk-like shape at the implant depth.
 15. The method of claim 14 andfurther comprising releasing the diamond above the disk like shape ofthe implant.
 16. The method of claim 15 wherein releasing the diamondcomprises implanting ions about outside edges of the diamond to bereleased.
 17. The method of claim 13 wherein the ions are implanted tomultiple depths.
 18. A method of forming structures in diamond, themethod comprising: forming a first mask on a diamond comprising a maskedportion and an unmasked portion; implanting ions through the firstmask's unmasked portion at multiple depths; forming a second mask on thediamond comprising a masked portion and an unmasked portion; implantingions through the second mask's unmasked portion at multiple depths priorto releasing at least a portion of the structure; and, releasing atleast a portion of the structure formed by the ion implantations. 19.The method of claim 18 wherein the diamond is a single crystal chemicalvapor deposition formed diamond.
 20. The method of claim 18 wherein ionsimplanted through the first mask's unmasked portion define an areabeneath the structure.
 21. The method of claim 18 wherein the ionscomprise hydrogen ions.
 22. The method of claim 18 wherein releasing thestructure comprises heating the diamond in a non-oxidizing environment.23. The method of claim 18 wherein the ions comprise carbon ions.
 24. Amethod of forming structures in diamond, the method comprising: forminga first mask on a diamond comprising a masked portion and an unmaskedportion; implanting ions through the first mask's unmasked portion atmultiple depths; releasing at least a portion of the structure formed bythe ion implantations in a non-oxidizing environment.